How to display index entries on the same line as the text being indexed

Question

Is it possible to let showidx display index entries on the same line as the text being indexed? It seems not as makeindx.pdf says:

This macro actually typesets the box containing all the index entries on the current page [...].

Which is a bit ironical since, in makeindx.pdf itself, the name of the macro being thereby described, \@mkidx, is in the margin, just in front of the text. (Of course, the environment seems different and \@mkidx is probably not an index entry. On the other hand, the text in cleveref.pdf, which also has margin entries, seems to be just ... text.)

So, given that I am already using hyperref, cleveref and tcolorbox, what might be an answer? Hopefully one that does not require yet another package.

Here is a rather long but minimal example:

% !TEX TS-program = pdflatexmk  
\documentclass{book}

    \usepackage{makeidx}
    \usepackage[hyperfootnotes=false]{hyperref}%[pdfborder={0 0 0}]

%Begin the ``quick and dirty hack'' due to Heiko Oberdiek which loads showidx 
\makeatletter
\ifHy@hyperindex
  \def\HyInd@ParenLeft{(}%
% Hook in \HyInd@@wrindex
  \let\HyInd@showidx\@empty
% Hook in \HyInd@@wrindex for package showidx
  \def\HyInd@showidx#1{%
    \@showidx{#1}%
    \if@nobreak
      \ifvmode
        \nobrak
      \fi
    \fi
  }%
% Load package showidx
  \let\siOrg@makeindex\makeindex
  \let\siOrg@@index\@index
  \let\siOrg@@wrindex\@wrindex
  \let\siOrg@index\index
  \RequirePackage{showidx}
  \let\makeindex\siOrg@makeindex
  \let\@index\siOrg@@index
  \let\@wrindex\siOrg@@wrindex
  \let\index\siOrg@index
    % rest of hyperref part
  \@ifpackageloaded{multind}{%
    \let\HyInd@org@wrindex\@wrindex
    \def\@wrindex#1#2{\HyInd@@wrindex{#1}#2||\\}%
    \def\HyInd@@wrindex#1#2|#3|#4\\{%
      \ifx\\#3\\%
        \HyInd@org@wrindex{#1}{#2|hyperpage}%
      \else
        \def\Hy@temp@A{#3}%
        \ifx\Hy@temp@A\HyInd@ParenLeft
          HyInd@org@wrindex{#1}{#2|#3hyperpage}%
        \else
          \HyInd@org@wrindex{#1}{#2|#3}%
        \fi
      \fi
    }%
  }{%
    \def\@wrindex#1{\@@wrindex#1||\\}
    \def\@@wrindex#1|#2|#3\\{%
      \ifx\\#2\\%
        \protected@write\@indexfile{}{%
          \string\indexentry{#1|hyperpage}{\thepage}%
        }%
      \else
        \def\Hy@temp@A{#2}%
        \ifx\Hy@temp@A\HyInd@ParenLeft
          \protected@write\@indexfile{}{%
             \string\indexentry{#1|#2hyperpage}{\thepage}%
          }%
        \else
          \protected@write\@indexfile{}{%
            \string\indexentry{#1|#2}{\thepage}%
          }%
        \fi
      \fi
      \endgroup
      \HyInd@showidx{#1}%
      \@esphack
    }%
  }%
\fi
\makeatother
%End the ``quick and dirty hack'' due to Heiko Oberdiek which loads showidx 

    \usepackage{cleveref}

        \newcounter{proc}
    \usepackage{tcolorbox}

%Begin the Sharpe (2013-01-18) code as modified by Schulz (2016-02-1) to have math in Showindex     
\let\oldopenparen\(
\let\oldcloseparen\)
\def\({\protect\oldopenparen}
\def\){\protect\oldcloseparen}
\newcommand{\INDEX}[1]{\index{#1}}
%End the Sharpe (2013-01-18) code as modified by Schulz (2016-02-1) to have math in Showindex               

\makeindex
\begin{document}    

Some text necessary to drown the words to be indexed. Some text necessary to drown the words to be indexed. \textbf{Oberdieck}\INDEX{Oberdieck}
Some text necessary to drown the words to be indexed. Some text necessary to drown the words to be indexed. 

\newpage

Some text necessary to drown the words to be indexed. Some text necessary to drown the words to be indexed.
\textbf{$\cup$}\INDEX{$\cup$}
Some text necessary to drown the words to be indexed. Some text necessary to drown the words to be indexed. 

\printindex
\end{document}